Hummingbirds are some of the most fascinating birds to observe in nature. With their ability to seemingly defy gravity and hover in midair while feeding, along with their high speed maneuvers and beautiful, iridescent plumage, they are a joy to watch. But telling the difference between a juvenile and an adult hummingbird can sometimes be tricky for an amateur birder. Here are some tips on how to identify a young hummingbird.
Size
One of the most obvious ways to differentiate an adult from a juvenile is size. Hummingbirds hatch from tiny eggs about the size of a jellybean. As you can imagine, newborn hummingbirds are extremely small. A juvenile will be about 2.5 inches long, whereas an adult may reach 3-5 inches in length depending on the species. The following table compares the average adult size to the average juvenile size of some common hummingbird species:
Species | Adult Size | Juvenile Size |
---|---|---|
Ruby-throated Hummingbird | 3.5 inches | 2.5 inches |
Rufous Hummingbird | 3.5 inches | 2.5 inches |
Allen’s Hummingbird | 3.5 inches | 2.5 inches |
Calliope Hummingbird | 3 inches | 2.5 inches |
So if you spot a particularly small hummingbird, chances are good it’s a young one. The minute size of juveniles is especially apparent if seen near an adult.
Bill size
Along with their petite stature, juvenile hummingbirds can be identified by having shorter bills than mature birds. As they develop, the bill length increases. An adult male hummingbird’s bill will account for about 1/3 of its total body length. On a juvenile, the ratio of bill to body size will be smaller. Examining the bill proportions is a helpful step in determining age.
Plumage
A juvenile hummingbird’s plumage will look incomplete compared to the full, brilliant colors of an adult. Males and females both start out with plain, drab feathers. The iridescent throats and vibrant plumage that hummingbirds are famous for develop later as the bird matures. Here are some key points regarding juvenile plumage:
- Lack vibrant coloration – Young hummingbirds will appear mostly gray/brown. Their throats will not have any coloring.
- Females are difficult to distinguish – Since adult females also lack bright plumage (except for some colored throat feathers), juvenile females nearly resemble adult females. However, they are paler overall.
- Tail feathers lack fork – Adult male hummingbirds have distinctive tail feathers that form a forked shape. Juveniles tails will be rounded or straight edged.
- Spotted chest – Many juvenile hummingbirds have speckled or spotted chest plumage that helps camouflage them in the nest. These spots disappear with maturity.
So if you notice a hummingbird that lacks vibrant coloration, tail forking, or defined throat patches, it is likely a juvenile.
Behavior
In addition to physical appearance, a hummingbird’s behavior can provide clues about its age. Here’s what to watch out for:
Flight
The rapid, specialized flying skills of hummingbirds are honed with time. Juveniles will appear unsteady and awkward when taking flight. Their wings may flutter more quickly as they work to stabilize themselves. Flight maneuvers are also less precise than adults. Young hummingbirds lack the aerobatic talents seen in mature birds, like sustained hovering ability.
Feeding
Adult hummingbirds have experience and skill when feeding. They know how to quickly dip their bills into flowers to extract nectar. Juveniles are still learning this technique, so they will fumble around more at flowers and feeders as they become accustomed to eating. Because of this, juveniles spend more time perching than adults. Their rest breaks conserve energy until their feeding skills improve.
Interactions with others
Juvenile hummingbirds are solitary and may interact minimally with others. They will devote most of their time to finding food rather than social activities. Adults, on the other hand, have bold personalities and freely interact. A territorial adult male will chase another male away from his food source. But a juvenile male would flee to avoid confrontation. The timid nature of young hummingbirds also distinguishes them from mature birds.
Curiosity
Juvenile hummingbirds are very inquisitive as they explore new areas for the first time. This innate curiosity motivates them to approach novel objects or get close to humans. They have yet to learn what is safe versus dangerous. As a result, juveniles may allow very close observation without being startled. An adult hummingbird would typically show more fear and keep its distance.
Time of Year
When you spot a hummingbird can also indicate if it is an adult or juvenile. Knowing the basic nesting season for hummingbirds helps narrow down when young birds will first leave the nest:
- In North America, most hummingbirds breed between February and July
- Eggs incubate for 2-3 weeks before hatching
- Chicks fledge the nest at 3 weeks old
- There are between 1-3 broods per season
- Juveniles from the first brood leave the nest as early as May
- Young hummingbirds then continue to appear through late summer
So if you notice smaller, clumsy hummingbirds in spring and summer, they are likely that year’s batch of juveniles experiencing life outside the nest for the first time. Spotting them during this period is easier than later in the year when they become more adult-like.
Differences by Species
It is also helpful to consider the range of the hummingbird species you spot as well as nesting timelines. Here are some examples:
- Calliope Hummingbirds range in the Pacific Northwest. New juveniles appear as early as mid-May.
- Ruby-throated Hummingbirds are found east of the Mississippi. Juveniles emerge starting late May through July.
- Rufous Hummingbirds nest along the Pacific Coast. Their juveniles leave nests from June-July.
- Allen’s Hummingbirds breed along California’s coast. Young fledge from April-July.
If you understand the fledging periods for your region, it makes recognizing juveniles easier.
Conclusion
Telling adult and juvenile hummingbirds apart comes down to a few key differences. Juveniles are smaller in size, with shorter bills and incomplete plumage lacking vivid coloration or patterns. Their flight skills are unrefined, feeding is awkward, and their behavior is timid and solitary compared to bold, territorial adults. These physical and behavioral cues, along with knowing it’s within the normal fledging period, are all helpful to identify immature hummingbirds. With a little practice, birders can soon recognize the distinction. Gaining skills to understand the life cycle of these special birds is rewarding.